1. Technical Field of the Invention
The present invention relates generally to a fuel injection system equipped with a fuel injector which is designed to change the amount of lift of a nozzle needle as a function of a stroke of an actuator, and more particularly to such a system designed to enhance the uniformity of the size of particles of fuel sprayed from a fuel injector.
2. Background Art
There are known common rail fuel injection systems equipped with a common rail for supplying high-pressure fuel to a fuel injector for each cylinder of a diesel engine. For instance, Japanese Patent First Publication No. 62-258160 discloses such a common rail fuel injection system which works to control the pressure of fuel to be supplied from the common rail to the fuel injector as a function of operating conditions of the engine. When the quantity of fuel sprayed from the fuel injector increases, the pressure of fuel in the common rail may be elevated to ensure the injection of fuel into the engine over a target injection duration.
The pressure of fuel in the common rail affects the shape of spray of fuel jetted from the fuel injector. The pressure of fuel in the common rail may, therefore, be regulated to achieve a desired shape of spray of fuel in order to ensure required output characteristics of the engine. The size of distributed particles of the sprayed fuel depends upon the pressure of fuel in the fuel injector, however, the particles of the sprayed fuel may be ununiform in size. It is, thus, difficult to uniform the size of all of the particles of the sprayed fuel in order to ensure the required output characteristics of the engine.
Japanese Patent First Publication No. 2003-214302 discloses the above type of conventional fuel injection system.